1902.J VOX IHERING — MOLLUSCAN FAUNA OF PATAGONIA. 133 



Lithodomus patagonicus d'Orb. Solecurius platensis d'Orb. 



Modiola iulipa Lam. Marginella prumivi Gm. 



Nucula piielchana d'Orb. Columbella acuta Stearns. 

 Tivela argentina Sowb. 



Of the nineteen species which the author regards as still existing 

 at least nine are incorrectly determined. Admitting that the 

 remaining ten species are accurately determined, the proportion of 

 living species in the Parana formation is as lo : 60, or 17 per cent. 



Borchert's attempt to prove that the Parana formation is Pliocene 

 must be regarded as a failure ; it is opposed to the opinion of 

 d'Orbigny, Philippi and von Ihering, all of whom were well 

 acquainted with South American marine MoUusca, both recent and 

 fossil. We must continue to regard the Parana formation as 

 Miocene, while the Pliocene of Argentina is represented in the south 

 by the Cape Fairweather beds, and in the north by the Tehuelche 

 formation. Of the latter the new collection of Carlos Ameghino 

 contains an instructive representation, with many new species of 

 Pectinidce, Carditidce and Veneridce. 



From the marine deposits in the upper part of the Pampean 

 fortnation I have a relatively large collection. As the species 

 are all still living, I am obliged at present to consider the " Pam- 

 peano superior" of Ameghino as Pleistocene, It is interesting to 

 observe that in this formation are two different horizons, the older 

 of which contains Ostrea arborea Ch., Purpura hcBtnastoma L., 

 and other species now common on the Brazilian coast, but which 

 are wanting in the later horizon, where they are replaced by Ostrea 

 puelchana d'Orb. and other Patagonian species. 



With regard to the Patagonian formation, many new forms are 

 contained in a large collection sent to me this year by Dr. Floren- 

 tino Ameghino, and gathered by his brother Carlos in the years 

 1899 and 1900. This great collection contains representatives of 

 three different faunas, but the greater part of it comes from the 

 Patagonian formation. As I have studied many important collec- 

 tions from this formation, and as my friend Dr. A. E. Ortmann has 

 also discovered many new forms in the collections of the Princeton 

 Expedition, it was very surprising to find a great number of new 

 and interesting forms in this new collection, I reserve the descrip- 

 tion of these new species until Dr Ortmann's report has been pub- 

 lished, and describe here only two of the most striking new species. 



